title: Low-temperature degradation of a Y-TZP ceramic after surface treatments.
abstract: The purpose of this study was to evaluate the influence of zirconia surface treatments on low-temperature degradation (LTD). Disc-shaped specimens were subjected to one of four surface treatments, denoted as C (control-no surface treatment), Si (air abrasion with 30 µm silica-modified alumina particles), Al (air abrasion with 30 µm alumina particles), and Gr (grinding with 120 grit diamond discs). Half of the samples were submitted to autoclave treatment for 12 h (127°C, 1.5 bar). Samples were characterized by x-ray diffraction and profilometer analysis and were subjected to biaxial flexural strength test. All of the groups exhibited an increase in the amount of monoclinic phase (m-phase) after LTD. The t→m transformation was remarkable for the specimens from the C group, which also exhibited a significant increase in strength. The Gr group also exhibited an increase in strength but lower initial roughness, which probably suppressed LTD on the zirconia surface. The specimens subjected to air abrasion exhibited higher initial amounts of m-phase and a small increase in m-phase after LTD; the strength was not affected in these groups. The effects of LTD were different with each surface treatment applied. Apparently, LTD may be suppressed by smoother surfaces or the presence of an initial amount of m-phase on zirconia surface.
authors.affiliation: Department of Dental Materials and Prosthodontics, Sao Paulo State University, Sao Jose dos Campos, São Paulo State, Brazil.
authors.forename: Marina
authors.initials: M
authors.lastname: Amaral
authors.forename: Luiz Felipe
authors.initials: LF
authors.lastname: Valandro
authors.forename: Marco A
authors.initials: MA
authors.lastname: Bottino
authors.forename: Rodrigo O A
authors.initials: RO
authors.lastname: Souza
mesh_terms: D000042:Absorption; D000388:Air; D001672:Biocompatible Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry; D018130:Diamond; D008422:Materials Testing; D016012:Poisson Distribution; D011312:Pressure; D015203:Reproducibility of Results; D012825:Silicon / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D014961:X-Ray Diffraction; D015019:Yttrium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; C499362:yttria stabilized tetragonal zirconia; D003776:Dental Porcelain; D015019:Yttrium; D018130:Diamond; D015040:Zirconium; D012825:Silicon
keywords: low-temperature degradation; strength; surface alterations; x-ray diffraction; zirconia ceramic